1. Field of the Invention
The present invention relates to a lens barrel and an image capture apparatus such as a camera having the same.
2. Description of the Related Art
In recently popular, compact zoom cameras, a zoom lens barrel needs to move in (collapse) and out (project) to cover its photographing range from a wide angle state to a telephoto state. A so-called collapsible type zoom lens barrel has also been put to practical use. The collapsible type zoom lens barrel is a zoom lens barrel which, when a camera need not perform photography, is collapsed into, and accommodated within, the body of the camera to make the camera more compact so that a user can easily carry the camera. In addition, in recent years, there have been increasing demands for higher (optical) zooming ratios, and higher zooming ratios lead to a larger difference between the length of a lens barrel in its wide angle state or its collapsed state and the length of the lens barrel in its telephoto state. To cope with this problem, it has been necessary to provide a lens barrel structure which can be extended to a longer length, i.e., a multi-segmented zoom lens barrel.
In addition, there are demands for further miniaturization of cameras having such zoom lens barrels. In view of these demands, numerous proposals have heretofore been made. Examples of arts related to the invention are a lens barrel described in Laid-Open Japanese Patent Application No. Hei 11-258,678 and a collapsible lens mechanism for a single-lens reflex camera described in Laid-Open Japanese Patent Application No. Sho 55-52,038.
The proposal described in the above-recited Laid-Open Japanese Patent Application No. Hei 11-258,678 is a camera including a lens barrel which is made of a first lens group which is stationary at the front position, a plurality of movable lens groups disposed behind the first lens group, optical axis varying means disposed between the front end and the rear end of an optical system composed of the plurality of movable lens groups for varying the direction of an photographing optical axis, and driving means for moving each of the plurality of movable lens groups that are disposed before and behind the optical axis varying means, in the direction of the photographing optical axis. This proposal aims at miniaturizing the entire camera by reducing the diameter of the first lens group lying at the front position (the front lens group).
The proposal described in Laid-Open Japanese Patent Application No. Sho 55-52,038 is a collapsible lens mechanism for a single-lens reflex camera which includes a mechanism for retracting a mirror from a photographing optical axis in combination with the collapsing operation of a lens. This proposal aims to miniaturize the entire camera by collapsing a photographing lens into a position from which the mirror has been retracted.
However, in the proposal described in the above-recited Laid-Open Japanese Patent Application No. Hei 11-258,678, a reflecting mirror which is the optical axis varying means is disposed before an aperture diaphragm, and a plurality of movable lens groups of a variable magnification lens system which indispensably needs a certain degree of moving distance to perform a zooming operation is accommodated in the camera body, so that it is extremely difficult to miniaturize the camera body.
The proposed camera described in Laid-Open Japanese Patent Application No. Sho 55-52,038 is provided with a mechanism for retracting a mirror from a photographing optical axis in combination with the collapsing operation of a lens and which can collapse a photographing lens into a vacant space from which the mirror has been retracted. This art has been practiced for the view finders of single-lens reflex cameras, but is not intended to be applied to picture taking optical systems.
Further, according to the art disclosed in Japanese Patent Laid-Open No. Hei 7-27,963, a zoom lens barrel has a three-step shifting mechanism. More specifically, it has a stationary tube on its outermost circumference, and has a structure which moves an inside frame from a collapsed position to a photography-enabled projected position by means of gears inside the stationary tube. It performs zooming from a wide angle end position to a telephoto end position.
The art disclosed in Japanese Patent Laid-Open No. Hei 8-313,788 has a structure which performs shifting from a collapsed position to a photography-enabled projected position by means of a lead screw and, after that, performs zooming by rotating an outer circumferential rotating frame.
The lens barrel disclosed in Japanese Patent Laid-Open No. Hei 11-72,682 can be driven to switchably perform a set-up shifting movement from a lens-barrel collapsed position to a photography-enabled projected position and a shifting movement within a zooming range. This lens barrel includes a set-up gear for shifting the above-described barrel frame from the collapsed position to the projected position, and a zooming gear for turning the barrel frame at the projected position to perform driving for zooming. The set-up gear and the zooming gear are supported on a stationary frame. Each of the set-up gear and the zooming gear uses an axially long gear which extends into a movement zone from the collapsed position to the projected position.